Macroecological correlates and spatial patterns of anuran description dates in the Brazilian Cerrado

Abstract

Aim To quantify the relationship between the description dates of anuran species in the Brazilian Cerrado and some macroecological traits, and to verify the spatial patterns of average description dates and their correlation with human occupation and biodiversity knowledge.Location Brazilian Cerrado (South America). MethodsThe average date of description of 131 species of anurans found in 181 cells overlaying the Brazilian Cerrado was recorded. Description date was regressed across species on body size and geographical range size. Phylogenetic effects that could bias the significance tests of the multiple regression model of description dates on macroecological traits were taken into account using a phylogenetic subtraction method in which families and genera were classificatory factors in a nested two-way analysis of variance (  ) model. We also conducted a spatial analysis of the average description date that was estimated for each cell. This cell-based metric was regressed on human population size, the year of foundation of the municipalities and the number of inventories undertaken in each cell. The influence of spatial autocorrelation patterns was taken into account by using the geographically effective number of degrees of freedom. ResultsThe number of new species being discovered in the Brazilian Cerrado has been increasing, especially over the last 50 years. Cross-species analyses indicated that description dates were negatively correlated with body size and geographical range size, taking phylogenetic effects into account. Even after controlling for the spatial structures in all variables, average description date was positively correlated with human population in geographical space, but because of multicolinearity structure in the data, it was not possible to quantify the independent influence of human population and number of inventories on description date. ConclusionsAs found in previous papers, large-bodied and widely distributed species are likely to be described first. Species yet to be discovered are probably small-bodied and with narrow distributions, more restricted to the Cerrado biome. Also, the explicit spatial approach showed that the average description date is spatially correlated with total human population and biodiversity knowledge in the Cerrado region. Our findings suggest that incorporating human population density into the reserve design algorithms, which has usually been done to avoid or minimize conservation conflicts, may also produce good results because this will preserve many places where most of the non-described species will probably be found in the future.

Anfíbios da Estação Ecológica Serra Geral do Tocantins, região do Jalapão, Estados do Tocantins e Bahia

“…Estes estudos revelam valores de riqueza comparáveis à de áreas inventariadas na porção centro-sul (Tabela 2), confirmando as previsões de Diniz-Filho et al (2005). Contudo, Pavan & Dixo (2004) reportam uma riqueza superior ao valor obtido por nosso estudo, com 52 espécies para as regiões da UHE Luís Eduardo Magalhães, em Palmas, Tocantins, baseado em um estudo de longa duração.…”

“…Diniz-Filho et al (2004) afirmam que os maiores valores de riqueza de anuros no Cerrado são encontrados na porção centro-sul. Todavia, em outro estudo mais recente que analisa a distribuição das espécies em relação a sua data de descrição, os mesmo autores discutem que a riqueza na porção norte do Cerrado deve ser mais alta do que os últimos estudos tem revelado, uma vez que boa parte dos inventários realizados até o início da década concentravam-se na porção central e sul do bioma (Diniz-Filho et al 2005). Apenas recentemente foram publicadas listas de espécies para a região centro-norte do Cerrado como para a UHE Luís Eduardo Magalhães, em Palmas, Tocantins (Pavan & Dixo 2004), Parque Estadual do Jalapão (Vitt et al 2005), vale do rio Tocantins, entre os Estados do Tocantins e Maranhão (Brasileiro et al 2007) e para a região de Balsas no Maranhão (Barreto et al 2007), revelando valores de riqueza maiores ou no mínimo comparáveis a outros locais dentro do domínio, e confirmando as hipóteses de Diniz-Filho et al (2005).…”

Out of the deep: Cryptic speciation in a Neotropical gecko (Squamata, Phyllodactylidae) revealed by species delimitation methods

“…The rate of species description in the Brazilian Cerrado is biased by unequal distribution of sampling efforts across the biome (Diniz-Filho et al, 2005. Even large-bodied cryptic squamate species were recently described following expeditions to previously unsampled regions (Giugliano et al, 2013;Nogueira and Rodrigues, 2006).…”

Agriculture, habitat loss and spatial patterns of human occupation in a biodiversity hotspot

“…The value expected under the null hypothesis of the absence of spatial autocorrelation is -1 / (n-1). Because significant spatial autocorrelation was detected in the OLS residuals using Moran's I autocorrelation coefficient, statistical tests are not strictly valid and this may create difficulties when interpreting the effects of predictors on habitat remnants (see Legendre & Legendre, 1998;Diniz-Filho et al, 2003). Moreover, it indicates that there are spatial components underlying variation in habitat remnants that are not taken into account by environmental predictors and human occupation, so that spatial regression methods could be used to assess these components.…”

“…Secondly, spatial patterns in response and predictor variables, as well as in model residuals, were assessed via Moran's I coefficients (Legendre & Legendre, 1998;Diniz-Filho et al, 2003). The spatial relationship among cells covering the Cerrado was based on a Gabriel's network (Figure 1b) (see Legendre & Legendre, 1998;Vieira et al, 2008).…”